Hydraulic double-action metaldrawing press



Feb. 7, 1939. w ERNST 2,146,534

HYDRAULIC DOUBLE-ACTION METAL DRAWING PRESS Filed July 22, 1955 INVENTOR W41 TEE 152M577 +JML . ATTORNEYS.

iatented Feb. 7, 1939 UNITED STATES PATENT OFFICE HYDRAULIC DOUBLE-ACTION METAL- DRAWING PRESS tion of Delaware Application July 22, 1935, Serial No. 32,479

9 Claims.

This invention relates to hydraulic presses. and especially to metal-drawing presses arranged for forming metal blanks into articles of different shapes, while the metal blank is clamped in position by means provided in the press.

One object of my invention is to provide a hydraulic double-acting press having a drawing piston and a clamping piston arranged to move into position at substantially the same time during the working stroke until the clamping position is reached, atter which the drawing piston continues the operation of forming the article, the drawing piston and the clamping piston being retracted together.

Another object is to provide a press of the above type, wherein the double-acting drawing piston has an annular area which may be made considerably smaller than the area of the ends of the clamping pistons so as to provide a rapid speed of retraction or pull-back.

Another object is to provide such a press, wherein the clamping and drawing operations, together with the retracting operation, are entirely automatic without any necessity of adjustment upon the part of the operator.

Another object is to provide a double-action hydraulic drawing press, wherein means is provided for automatically directing the excess fluid into the tank upon the reversal of the pump.

The drawing illustrates a front elevation, partly in section and somewhat diagrammatic, of a hydraulic double-acting metal-drawing press embodying my invention, together with a hydraulic circuit for actuating this press.

Referring to the drawing in detail, the hy-.

draulic press shown as embodying my invention, consists of a base I, which is connected by the tie rods 2 to a top member 3, these being secured upon the tie rods 2 by nuts 4, threaded upon the threaded portions 5 thereof. Mounted upon the base is a die 6, having a recess or forming portion I, of the shape necessary for producing the particular article which it is desired to make. Theforming portion 1 is provided with a port 8 5 communicating with a pipe 9, the latter being arranged to provide compressed air for ejecting the finished article after the drawing operations have taken place. The metal blank I0 is shown in position upon the die 6 before any of the operations mouths of the clamping cylinders |2 are provided with similar glands l4, arranged to compress packings l6. These packings prevent the escape of fluid from the clamping cylinders and drawing cylinder.

Arranged to reciprocate in the main cylinder I is the main piston rod l1, having a piston head l8, the piston rod passing through the aperture in the gland l3 and packing l5. To the lower end of the piston rod I1 is attached a platen l9 having a die member secured thereto. The die member 20 corresponds in configuration to the forming portion 1 of the die member 6, but is of opposite shape so that the two portions 1 and 20 cooperate to form the finished article between them from the metal blank Ill.

The clamping cylinders l2 are provided with clamping pistons 2| passing through the apertures in the glands I4 and packings l6, and secured to a tie member 22, which serves to interconnect their lower ends. Secured to the tie member 22 is a clamping member 23, as by the bolts 24. Beneath the clamping member 23 is arranged a blank holder 25, the latter resting upon the metal blank Hi from which the article is formed. An aperture 26 in the blank holder permits the passage of the die member 20 therethrough.

The main piston head I8 is of the doubleacting type, having a working face 21 and a pull-back face 28, the latter being of annular shape and constituting the space beneath the piston head l8 and surrounding the piston rod Similarly, the clamping pistons 2| are provided with working faces 29. In my invention, by the arrangement subsequently to be described, the annular pull-back area 28 may be made substantially smaller than the combined areas of the working faces 29 of the clamping pistons 2|. Previously, it has been considered necessary to make the annular area 28 equal to the combined areas of the working faces of the clamping pistons 2|, plus an additional area sufficient to sustain the weight of the moving parts so as to raise them against gravity. This construction, however, caused a slow action of the parts, whereas in my present construction the comparatively small annular area of the pull-back portion 28 enables a very rapid withdrawal or pull-back of the main platen. The main platen l9 and the tie member 22 move downwardly in an independent manner, although substantially simultaneously. On the upward or retraction stroke, however, the main platen engages the tie member in the shouldered portions 80, raising the tie member and with it the clamping pistons 2|.

Mounted on top of the main drawing cylinder II is a. fluid reservoir or surge tank 3|. Within this tank 3| is mounted a surge valve 32, of the type disclosed in my prior patent, No. 1,892,568, issued December 27, 1932. This surge valve serves the purpose of admitting fluid to the interior of the main drawing cylinder II from the tank 3|, while the main piston head I 8 is descending by gravity during the initial part of its working stroke. The surge valve 32 also is arranged so that it opens during the retracting or pull-back stroke of the main piston head I8, thus discharging fluid from the main cylinder back into the tank 3|. The mechanism for so actuating the surge valve is operated by pressure fluid passing into the surge valve 32, along the pipe 33.

The pipe 33 is joined to the pipe 34, connected at one end to the pressure release valve 35. The latter is, in turn, connected by the pipes 38 and 31 to the by-pass valve 38. A choke valve 39 serves to restrict the flow of fluid through the pipe 31 from the pressure release valve 35, whereas a similar choke valve 48 on the pipe 4| discharges fluid directly into the tank 3| from the pressure release valve 35. The details of the pressure release valve 35, the by-pass valve 38 and their associated valves and pipes, form no part of the present invention, but may be found fully disclosed in my prior patent, No. 1,956,758, issued May 1, 1934. The purpose of these valves 35 and 38 is to release the fluid pressure in the main cylinder prior to the opening of the surge valve, and also to by-pass the return of the pump discharge to the surge tank 3| through the by-pass valve 38 during the release of the pressure fluid through the release valve 35. The pipe 42 leads from the main cylinder I to the pressure release valve 35, and serves to convey the pressure fluid from the former to the latter.

The pipe 34 leads into a T-coupling 43, one end of which is provided with a check valve 44, opening in a direction to permit fluid to pass out of the surge tank 3| into the T-connection 43 in the direction of the arrow, but not in the reverse direction. From the T-connection 43 the pipe 45 goes to one side of the check valve 46. The latter opens in the direction of the arrow, that is, in a direction away from the surge tank 3|. Beyond the check valve 46 the pipe 41 leads downward to the intake coupling 48 of the pump 49. The pump 49 may be of any suitable type, the details of which form no part of the present invention. From the pressure or discharge coupling 58 of the pump 49 the pipe 5| leads to the port 52 in the head of the main drawing cylinder I Leading from the space below the piston head I8 is the port 53 and the pipe 54, having the branch 55 leading downward to the central port 56 of the control valve 51, described in detail below. The pipe 54 terminates in the check valve 58, opening in a direction toward the main cylinder I, as indicated by the arrow. Beyond the check valve 58 the pipe 59 runs to the intake coupling 48 of the pump 49.

Also connected to the intake coupling 48 is the pipe 68, leading from the right end port 6| of the main control valve 51. The pipe 62, leading from the side ports 63 and 64 of the control valve 51 to the port 65 of the surge tank 3|, conducts fluid from the control valve 51 back to the surge tank 3|. From the remaining port 66, on the upper side of the main control valve 51, the pipe 81 leads to the port 88 in one of the clamping clamping cylinders |2 so as to conduct fluid between them. From the port 13 in the surge tank 3| the line 14 conducts fluid through the check valve I2 and the port 1 into the left-hand clamping cylinder l2. The check valve 12 opens in a direction away from'the surge tank 3|, in the direction of the arrow.

Leading from the port 15 in the right-hand clamping cylinder I2 is the passage 16, opening into the interior of the check valve 11. The latter has a plunger 18 urged to close the port 19 thereof by the spring 88. Leading from the interior oi the check valve 11, through the port 8| thereof,'is the pipe 82. s The latter runs to the port 83 in the wall of the surge tank 3|.

The pump 49 may be of any suitable type, preferably of the reversible type. The interior of the main control valve-51 is provided with a main bore 89, within which is mounted a valve rod 98, having thereon a pair of spaced heads 9| and 92, respectively. The coil spring/93 surrounds the left-hand end of thevalve rod 88, and urges the valve heads 9| and 92 to the right. Beyond the valve head 92 the valve rod 98 continues in a pilot piston 94, arranged to reciprocate in a pilot cylinder 95 forming, in effect, an extension of the main bore 89, but of smaller diameter.

The valve heads 9| and 92 are so spaced that in one position, as shown, they permit fluid to pass from the port 56 through the space between them, into the port 86. In the other position, however, as when the pilot piston 94 is shifted. by the fluid pressure in the pilot cylinder 95, fluid is permitted to pass from the port 66, through the right-hand end of the main bore 89, into the port 64, and thence into the discharge line 62, returning to the surge tank 3| through the port 85,

In the operation of the circuit, the metal blank H), from which the articles of various shapes are to be produced, is first placed upon the die member 6. The pump 49 is started and the main plunger |'||8 is then allowed to descend by gravity, together with the clamping plungers 2| and the tie member 22 until the blank holder 25 engages the edges of the blank l8, clamping it against the die 6. During this period the surge valve 32 operates to permit fluid to be drawn into the space above the main piston head l8 from the surge tank 3| in order to preflll the main cylinder. Similarly, fluid is drawn into the clamping cylinders during their descent by fluid expelled from the space beneath the main piston head l8, through the port 53, lines 54 and 55, port 56, main bore 89, port 68, line 81 and port 68 into the right-hand clamping cylinder l2. The line 10 conveys this fluid to the left-hand clamping cylinder l2. Any deficiency in the supply of fluid required by the clamping cylinders I2 is compensated for by the action of the check valve 12, through which additional fluid is drawn into the clamping cylinders |2 from the surge tank 3 Meanwhile, the pump 49 has been discharging pressure fluid through the coupling 50, line 5| and the blank I downward into the corresponding forming portion 1 of the lower die 6.

The pressure continues to build up within the clamping cylinders I2 until it becomes suflicient to force the valve member I8 of the check valve 11 to the right, permitting fluid to escape through the check valve 11 by way of the pipe line 82, through the port 83 into the surge tank 3 I. Thus, by adjusting the tension of the spring 80, as by tightening the threaded plug 96, the c amping pressure may be varied byvarying the redetermined pressure at which the check valve II will open.

After the completion of the pressing operation the direction of flow of the fluid from the pump 49 is reversed, as by shifting the control lever I I0, so that the pressure fluid now discharges through the coupling 48, into the line 59, and thence through the check valve 58,'the line 54 and the port 53 into the space beneath the piston head I8. At the same time pressure n (1 goes through the line 60 and port 6I into the pilot cylinder 95, forcing the pilot piston 94 to the left and shifting the head 92 into a position to permit fluid to pass from the port 66, through the bore 89 and into the opposite port 64. In this position the fluid displaced by the clamping plungers 2I during their upward motion passes outward through the port 68, the line 61., the port 66, the bore 89, the port 64, the line 62 and the port 65 into the surge tank 3 I.

The rising of the main piston head I8 causes the platen I9 to engage the portions 30 of the tie member 22, thus causing the main plate'n to raise the clamping plungers 2I. During the return stroke of the press, pressure also goes through the line 45 and the coupling 43 to the pressure release valve 35 and by-pass valve 38, thus assisting in the discharge or the fluid from the space above the main piston head I8 through the line 42, in the manner described in the previously mentioned Ernst Patents Nos. 1,892,568 and 1,956,758.

Thus, it will be seen that the action of the press on the return stroke is entirely automatic, and there are no adjustments necessary to be made by the operator. The pilot piston 94 is thus responsive concomitantly to the reversal of the pump 49 to take care of the shifting of the valve 51 in such a manner as to properly discharge the fluid from the clamping cylinders I2 without any attention being required upon the part of the operator. At the same time, also, the fact that the annular area 28 on the under side of the piston head I8 is less than the combined area of the clamping plunger heads 29, causes the main piston head I8 to have a higher pull-back speed than in the previous devices; wherein these areas were substantially equal. Consequently, faster operation of the press, with greater efliciency during production, is therefore enabled by this construction.

It will be understood that in place of using a reversible pump 49, I may employ a reversing valve to reverse the direction of the flow of fluid in any suitable way, as is well known to those skilled in the art.

I desire to comprehend within my invention such modifications as may be embraced within my claims and the scope of my invention.

Having thus fully described my invention, what I'claim as new and desire to secure by Letters Patent, is:

1. In combination, a pressing cylinder, a double-acting pressing plunger therein having a plunger-advancing area and a plunger-retracting area, a clamping cylinder, a clamping plunger therein, a pump for supplying fluid to one of said plungers having means associated therewith for selectively directing pressure fluid to said plunger-advancing and plunger-retracting areas re-' spectively, and fluid-operated valve means auto matically actuated by the flow of pressure fluid to saidplunger-retracting area into a position for releasing the fluid from said clamping cylinder.

2. In combination, a pressing cylinder, a double-acting pressing plunger therein having a plunger-advancing area and a plunger retracting area, a clamping cylinder, aclamping plunger therein, a pump for supplying fluid to one of said plungers having means associated therewith for selectively directing pressure fluid to said plungeradvancing and plunger-retracting areas respectively, valve means arranged in one position to release the fluid from said clamping cylinder, and fluid-operated means automatically/actuated by the flow of pressure fluid to said plungerretracting area for automatically shifting said valve means with its fluid-releasing position to release said fluid from said clamping cylinder.

3. In combination, a pressing cylinder, a double-acting pressing plunger therein having a plunger-advancinng area and a plungefl'e'tracting area, a clamping cylinder, a clamping plunger therein, a pump for supplying fluid to one of said plungers having means associated therewith for selectively directing pressure fluid to said plunger-advancing and plunger-retracting areas respectively, valve means arranged in one position to release the fluid from said clamping cylinder, a servo-cylinder, and a servo-piston in said servocylinder operatively connected to shift said valve, said servo-piston beingautomatically actuated by the flow of pressure fluid to said plunger-retracting area for automatically shifting said valve into its fluid-releasing position to release the fluid from said clamping cylinder.

4. In combination, a pressing cylinder, a reversible pressing plunger therein, a clamping cylinder, a clamping plunger therein, a pump for supplying fluid to one of said plungers having means associated therewith to reverse the flow of fluid between said pump and said pressing cylinder, and a valve having a valve casing and a movable valve member therein adapted in a first position to effect flow of fluid from said pressing cylinder to said clamping cylinder and in a second position to release fluid from said clamping cylinder while preventing flow of fluid from said pressing cylinder to said clamping cylinder.

5. In combination, a pressing cylinder, a reversible pressing plunger therein having associated therewith a plunger-advancing area and a plunger-retracting area, a clamping cylinder, a clamping plunger therein, a pump for supplying fluid to one of said plungers having means associated therewith for selectively directing pressure fluid to said plunger-advancing and plungerretracting areas respectively, a valve having a valve casing and a movable valve member therein adapted in a first position to effect flow of fluid from said pressing cylinder to said clamping cylinder and in a second position to release fluid from said clamping cylinder while preventing flow of fluid from said pressing cylinder to said clamping cylinder, and means actuated by the flow of pressure fluid to said plunger-retracting area to shift said valve from said first position to said second position.

6. In combination, a. pressing cylinder, a reversible pressing plunger therein, a clamping cylinder, a clamping plunger therein, a pump for supplying fluid to one of said plungers having means associated therewith to reverse the flow of fluid between said pump and said pressing cylinder, a valve having a valve casing and a movable-valve member therein adapted in a first position to effect flow of fluid from said pressing cylinder to said clamping cylinder and in a second position to release fluid from said clamping cylinder while preventing flow of fluid from said pressing cylinder to said clamping cylinder, and escape valve means adapted to open at a predetermined pressure and release fluid from said clamping cylinder.

7. In combination, a pressing cylinder, a reversible pressing plunger therein, a clamping cylinder, a clamping plunger therein, a pump for supplying fluid to one of said plungers having means associated therewith to reverse the flow of fluid between said pump and said pressing cylinder, a valve having a valve casing and a movable valve member therein adapted in a first position to effect flow of fluid from said pressing cylinder to said clamping cylinder and in a second position to release fluid from said clamping cylinder while preventing fiow of fluid from said pressing cylinder to said clamping cylinder, and escape valve means adapted to open at a predetermined pressure and release fluid from saidclamping cylinder, said escape valve means being operative to discharge fluid while said valve remains in said first position to effect flow oi fluid from the pressing cylinder to the clamping cylinder.

8. In combination, a. reversible pressing plunger, a platen connected thereto, a clamping plunger, a clamping member operated thereby, valve means in a first position providing interfiow of pressure fluid between said clamping plunger and one side of said pressing plunger and in a second position providing discharge of fiuid from the space around said clamping plunger while preventing said interfiow of pressure fluid, and escape valve means associated with said clamping plunger to release the pressure fluid from the space therearound when the clamping pressure thereof reaches a predetermined amount.

9. In combination, a reversible pressing plunger, a platen connected thereto, a clamping plunger, a clamping member operated thereby, valve means in a first position providing interflow of pressure fluid between said clamping plunger and one side of said pressing plunger and in a second position providing discharge of fluid from the space around said clamping plunger while preventing said interfiow of pressure fluid, escape valve means associated with said clamping plunger to release the pressure fluid from the space therearound when the clamping pressure thereof reaches a predetermined amount, and a tie member releasably interconnecting said pressing plunger and said clamping plunger, said tie memher being arranged to permit said platen to continue its motion after said clamping member has reached its clamping position.

WALTER. ERNST. 

